Predicting POC export from plankton diversity

Calipsocean meeting

Thelma Panaïotis

05/03/2024

Aim

Environment, plankton and carbon

env env plankton* plankton* env->plankton* carbon export** carbon export** env->carbon export** plankton*->carbon export**

Questions

  • Can POC be predicted from env?
  • Can POC be predicted from plankton?
  • Can plankton be predicted from env?
  • Can POC\{env} be predicted from plankton\{env}?

Data

POC

POC export at 1000 m

Environment

As in Wang et al., 2023:

  • temperature

  • silicate

  • oxygen

  • NPP → Zeu

  • DIP, DIC, ALK, DOC

Plankton

UVP5 dataset: 2876 profiles

Plankton - Taxonomy

  • taxonomic richness

  • taxonomic diversity (Shannon)

  • taxonomic evenness (Pielou)

  • others to come…

Plankton - Morphology

Function diversity metrics (Magneville et al. 2022)

→ morphological diversity metrics (Beck et al., 2023)

  • morphological richness

  • morphological divergence

  • morphological evenness

  • …

Plankton - Trophic Status

Coming soon (no plankton trophic database to my knowledge).

  • Trophic status of a chaetognath

  • Trophic status of a copepod?

    • by size?
    • by region?

Other dataset? ↑ taxonomic resolution but ↓ coverage.

Final dataset

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468 data points

Final dataset – Splits

Learning* VS test set, stratified by POC.

What about spatial & temporal autocorrelation?

ML Model

(Multivariate) boosted trees

Response variable:

  • uni- or multivariate

  • ~normally distributed → log(POC)

Flexibility for predictors, handles interactions.

Complex & non-linear relationships.

Easy interpretation & implementation.

Results

POC from env

POC ~ temperature + silicate + Zeu + oxygen

R² = 81.6%

Good prediction!

POC from plankton

POC ~ all plankton metrics

R² = 49.5%

OK prediction!

Best predictors:

  • ta. evenness

  • ta. diversity

  • mo. richness

POC from plankton best predictors

POC ~ ta_eve + ta_div + mo_ric

R² = 46.0%

OK prediction!

plankton best predictors from env

ta_eve + ta_div + mo_ric ~ temperature + silicate + Zeu + oxygen

Mult. R² = 41.8%

OK prediction!

POC\{env} from plankton\{env}

POC_res ~ ta_eve_res + ta_div_res + mo_ric_res

R² = 1.2%

Bad prediction!

Conclusion

  • Can POC be predicted from env? → Yes
  • Can POC be predicted from plankton? → Yes
  • Can plankton be predicted from env? → Yes
  • Can POC\{env} be predicted from plankton\{env}? → No